Guiton came off the bench in relief to lead touchdown drives in the final minute of regulation and in overtime, with Carlos Hyde scoring on a 1-yard run to clinch No. 7 Ohio State’s 29-22 victory over Purdue on Saturday.

Purdue (3-4, 0-3 Big Ten) led 22-14 when Ohio State got the ball with just 47 seconds left in regulation. Guiton, inserted when Miller went out with an undisclosed injury, hit Chris Fields on a 2-yard touchdown pass with 3 seconds remaining. Guiton then found freshman Jeff Heuerman on the conversion pass to tie it at 22.

Hyde scored on a short plunge for Ohio State (8-0, 4-0) before Purdue’s Caleb TerBush, who had two TD passes, misfired on four passes in the overtime.

Purdue had earlier scored on TerBush TD passes of 83 yards to Akeem Shavers — on the first offensive play of the game — and 31 yards to Gary Bush in the third quarter, along with Akeem Hunt’s 100-yard kickoff return. The Boilermakers also picked up a safety when Ohio State was called for an illegal block in the end zone in the fourth quarter.

Miller completed 9 of 20 passes for 113 yards with an interception and ran for 47 yards on 12 carries before leaving the game on the next-to-last play of the third quarter.

After Ohio State got the ball on Bradley Roby’s blocked field goal, Miller took the ball on first down from the 24, stiff-armed a defender and sped around right end before being caught by cornerback Josh Johnson, who threw him hard to the turf on his left shoulder.

Miller didn’t get up for several minutes — he was in obvious pain — while he was attended by several doctors and trainers. Eventually he sat up, then stood on shaky legs for at least 60 seconds before he was led to the sidelines. He was later taken to the locker room by cart.

Guiton, in coach Urban Meyer’s doghouse this spring, came in to replace him.

The teams had traded touchdowns in the third quarter, with Ohio State taking a 14-13 lead on Hyde’s 2-yard run, set up by a 35-yard Miller-to-Chris Fields pass on which the Boilermakers blew the coverage.

Purdue answered by retaking the lead on TerBush’s quick pass to the right flank where Bush picked up a key block from Crosby Wright while racing untouched 31 yards for the score and a 20-14 lead.

The Buckeyes drove to a fourth down at the Purdue 33, where Drew Basil’s 50-yard field goal attempt hit the left upright flush and bounced away on the third play of the fourth quarter.

Ohio State took over at its own 39 with 47 seconds left in regulation. On first down, Guiton — who almost quit the team earlier this year — threw a long pass to a wide-open Devin Smith for a 39-yard gain on first down.

Battling the clock, the Buckeyes eventually faced a first and goal at the Purdue 2 with 3 seconds left. Guiton rolled to his left and fired a low pass to Fields. The play was reviewed but was allowed to stand.

Now down by two points, the Buckeyes set up for the conversion. Guiton lofted a soft toss over the linebackers to Heuerman to tie it.

After smothering the Boilermakers on the ensuing kickoff, the overtime was decided early.

Guiton led the Buckeyes steadily and Hyde gave them their biggest lead of the game on a 1-yard burst.

TerBush, who finished 19 of 30 passing for 230 yards with one interception, had a pass dropped to start the overtime and then threw three incompletions. Fans flooded on the field in celebration after his fourth-down pass hit the ground.

Guiton hit on 6 of 11 passes for 77 yards and the one touchdown with one interception. Hyde ended up with 91 yards on 19 carries and two touchdowns.

Purdue led 13-7 at the half on the strength of two huge, end-to-end plays.

On the first snap of the game, TerBush floated a pass into the left flat to Shavers who had slipped behind the coverage of linebacker Storm Klein. Shavers had to wait for the pass, caught it, then left Klein grasping at air as he completed the play untouched.

The Buckeyes, who have gotten off to slow starts all season on offense, did so again. They punted after each of their first two possessions before mounting a drive to take the lead.

On fourth and 2 at the Purdue 46, Hyde bounced off a teammate and cut off left tackle for a 21-yard gain and a first down. On third and 10 at the 25, Miller then hit Corey Brown on a crossing pattern for 17 yards. On the next play, Miller used a nifty fake on a handoff to Hyde and skirted right end for the 8-yard touchdown.

The Buckeyes held the lead for exactly 12 seconds.

Hunt took the ensuing kickoff 2 yards deep in the end zone and appeared to slightly hesitate before cutting to the right sideline while picking up blocks. He cut back to the right hash, then outran two defenders thanks to another slick cut to the right sideline to complete the 100-yard return for the 13-7 lead.

The Boilermakers defense had been ravaged in its last two outings, both at home: a 44-13 loss to Michigan and a 38-14 defeat to Wisconsin. It surrendered an incredible 82 points, 771 rushing yards and 1,054 yards.

But the Buckeyes, with one of the most volatile offenses in the nation, were held to 342 yards.